Last week, Thermwood completed installation of what is believed to be the world’s largest composite material 3-D printer at digital OEM Local Motors. The 10’x40′ printer is going to be used to produce the Olli – Local Motors’ self-driving, 3-D printed electric car with the advanced cognitive computing capabilities of IBM Watson. Passengers can interact conversationally with Olli while traveling from point A to point B and ask questions about how the vehicle works, where they are going and why Olli is making specific driving decisions.

As Thermwood explains, the printer is one of its signature Large Scale Additive Manufacturing (LSAM) machines, the industry’s first line of extrusion 3-D printers with built-in CNC machining capabilities. LSAM is used to produce large components from fiber-reinforced thermoplastic composite materials. The machine uses a two-step, near-net-shape production process.

The part is first 3-D printed layer by layer, to slightly larger than the final size, then it is trimmed to its exact final net size and shape using a CNC router. The process operates in free space and does not require molds or tooling. LSAM machines perform both printing and trimming on the same machine using two gantries, one for printing and one for trimming.

The machines function differently than Cincinnati Incorporated’s Big Area Additive Manufacturing (BAAM) machines, which were used to make various molds and parts for Local Motors’ pilot program for the Olli in 2016. One key difference between BAAM and LSAM is their extrusion capabilities. While the BAAM system can print 80 pounds of material per hour, Thermwood has three different printheads that are capable of deposition rates of 150, 300 and even 500 pounds per hour.

Additionally, the BAAM system features a ring-shaped mechanism for compressing the material as it’s printed, while the LSAM uses a servo-controlled wheel that follows behind the deposited polymers, packing them down. The BAAM system also relies on a moving printbed for control over Z-axis height, unlike the LSAM, which has a fixed bed and raises the extruder or router. While the BAAM is available with a print volume of 20 ft x 7.5 ft x 6 ft, the printing envelope of the LSAM is 10 feet wide and 5 feet tall, but the bed can be extended up to 100 feet or higher, if needed. The LSAM 3-D prints using industrial pellets from Techmer PM that have a ratio of 80 percent ABS plastic and 20 percent carbon fiber.